Method and system for relay attack prevention incorporating motion

ABSTRACT

A method and system for detecting if a relay is present in a PEPS system for a vehicle is provided by (a) determining whether movement of an authentication device was detected within a predefined time period after the authentication device enters a PEPS entry operational region; and (b) determining if the authentication device was stationary for a predetermined time period during a PEPS entry triggering event.

FIELD OF THE INVENTION

The present invention relates to passive entry passive start (PEPS)systems and in particular, detection and/or prevention of relay attackson PEPS systems in vehicles used to enter and/or start to the vehicle.

BACKGROUND INFORMATION

PEPS systems allow authorized users (with a valid key fob) tolock/unlock and start their vehicle without having to interact with theremote control (i.e. authorized key fob). The PEPS system may unlock orstart the vehicle via a manually triggered input request (capacitivesensor, push button, etc.) if the key fob is determined to be in a validPEPS region.

A PEPS system may define operating regions such that if an authorizedkey fob is located within the correct operating region then the vehiclewill respond to lock/unlock and start requests. PEPS regions can bedefined by low frequency (LF) signal fields emitted from antennas on thevehicle. A received signal strength indicator (RSSI) is typicallyimplemented in the authorized key fob as an abstraction of the magneticfield strength. The PEPS system may define the external operatingregions and internal operating regions using the RSSI signal levels fromthe various antennas on the vehicle. If an authorized key fob is locatedwithin the correct regions, i.e., the RSSI levels correspond to adefined region then the vehicle will respond to lock/unlock and startrequests.

A problem associated with PEPS systems is that vehicle thieves mayutilize what is known as a “relay attack” to steal the vehicle. Therelay attack tricks the PEPS system into believing that the thief is anauthorized user (in a defined operating region).

A relay attack generally requires two thieves (“Thief A” and “Thief B”)together with the authorized user (i.e. vehicle owner or other possessorof the key fob) being the same vicinity. A relay attack involvesextending the range of the LF field so that an authorized key fob whichis not in proximity of the vehicle will receive the LF challenge signal.“Thief A” carries a relay receiver (to receive the LF signal) and islocated close to the vehicle while “Thief B” carries relay transmitter(to retransmit the LF signal) and is located in close proximity to theauthorized key fob. In an “analog relay”, the relay receiver receivesthe LF signal then up-converts the frequency to a radio frequency (RF)and transmits it over an RF link to the relay transmitter. The relaytransmitter receives the RF signal and the down-converts the RF signalto LF and re-transmits the LF signal to an authorized key fob. Analogrelays are independent of the modulation and encoding of the LF signal.Other relay configurations are possible, for example, a “digital relay”where the relay receiver demodulates the LF signal and then the datastream is modulated over RF and transmitted. The relay transmitterdemodulates the RF signal and then the data stream is modulated over LFand re-transmitted.

A key fob automatically transmits an RF response upon receiving the LFchallenge. The RF response signal will typically transmit betweenapproximately 20-200 m back to the vehicle. If the vehicle receives thisresponse then it will assume that the key fob is in the vicinity of thevehicle and so the request will be authenticated. In addition, the relayattack method may also be applied to extend the range of the RF responserange beyond the transmit range of the key fob.

In summary, in a relay attack, thieves are able to enter and start avehicle when the key fob is outside its normal operating regions byrelaying messages from one location to another to make the vehicleappear closer to the key fob.

Techniques exist which aim to prevent relay attack by analysis of thePEPS LF and UHF signals, for example measuring the time of flight,signal vector checks and/or signal superposition, etc. These techniquesare generally complicated, ineffective or expensive.

A further problem is that, the PEPS system is vulnerable to a “drivewayattack”. The scenario whereby a person parks their vehicle in theirdriveway and then leaves the vehicle key fob in the house in closeproximity to the exterior walls is not difficult to imagine. The“driveway attack” simply requires the thief (Thief A) to trigger themanual input unlock request (capacitive sensor, push button, etc. on adoor handle) and relay the LF signals to another thief (Thief B)standing outside the walls of the house. Thief B can then relay thesignals into the house. If the key fob is situated close enough to theexterior walls, for example, behind the front door of the vehicleowner's house, then the key fob may receive the signal and send an RFresponse to unlock or start the vehicle upon request.

In order to prevent a “driveway attack”, techniques have been developedwhich focus on the movement of the key fob relative to the vehicle todetermine if there is an attack, for example, the key fob LF receiver isdisabled when the key fob is not moving for a predetermined time therebynot permitting a thief access to the vehicle.

A problem with the prior art approaches is that they are limited in thecomplexity of movements. For example, JP 2011052505A discusses a relayattack countermeasure for a PEPS system utilizing a motion sensor in akey fob to track the key fob movement from outside to inside thevehicle. A limitation with this arrangement is that it does not detectany change in key fob motion, e.g., from movement to stationary, it onlydetects that the key fob is moving.

Patent document US 2015/0302673 A1 discusses a relay attackcountermeasure for a PEPS system utilizing a key fob with a motionsensor to track the key fob movement to determine the distance travelledbased on the key fob speeds and the RSSI data.

Patent document U.S. Pat. No. 9,002,540 B2 discusses a relay attackcountermeasure for PEPS system utilizing a motion sensor to detect andstore the last key fob movement (within a predetermined time window)before an entry request. Vehicle entry is only permitted if the lastrecorded key fob movement occurs within the predetermined time window.

Patent document US 2014/0375423 A1 discusses a relay attackcountermeasure for a PEPS system utilizing a motion sensor to detectthat the key fob is moving before an entry request. Vehicle entry isonly permitted if the key fob has stopped moving when an entry requestis made. In addition, Vehicle start is only permitted if the key fob isstationary when a start request is made.

A problem with all of these prior art arrangements is that they cannotdetermine whether the key fob was in motion when entering the LF fieldin the vicinity of the vehicle or detect any complex movements of thekey fob.

Before turning to a summary of the present invention, it will beappreciated that the discussion of the background to the invention isincluded to explain the context of the invention. This is not to betaken as an admission that any of the material referred to is published,known or part of the common general knowledge.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides, a method ofdetecting if a relay is present in a PEPS system for a vehicle includingthe steps of: (a) determining whether movement of an authenticationdevice was detected within a predefined time period after theauthentication device enters a PEPS entry operational region; and (b)determining if the authentication device was stationary for apredetermined time period during a PEPS entry triggering event.

According to a second aspect, the present invention provides, a methodof detecting if a relay is present in a PEPS system for a vehicleincluding the steps of: (a) determining if an authentication device wasstationary for a predetermined time period during a PEPS entrytriggering event; and (b) upon a PEPS start sensor on the vehicle beingtriggered: (i) determining whether movement of the authentication devicewas detected before the PEPS start sensor on the vehicle was triggered;and (ii) determining whether the authentication device was detected asstationary for a predefined time period during the PEPS start triggeringevent.

According to a third aspect, the present invention provides, a method ofdetecting if a relay is present in a PEPS system for a vehicle includingthe steps of: (a) determining whether movement of an authenticationdevice was detected within a predefined time period after theauthentication device entered a PEPS entry operational region; and (b)determining if the authentication device was stationary for apredetermined time period during a PEPS entry triggering event; and (c)upon a PEPS start sensor on the vehicle being triggered: (i) determiningwhether movement of an authentication device was detected before thePEPS start sensor on the vehicle was triggered; and (ii) determiningwhether the authentication device was detected as stationary for apredefined time period during the PEPS start triggering event.

The authentication device may be a key fob, mobile communication deviceor RF device. The PEPS operating regions may be defined by LF magneticfields emitted from antennas on the vehicle. RSSI may be utilized in thekey fob and the PEPS system may define the external operating regionsand internal operating regions using the RSSI signal levels measuredfrom the various antennas on the vehicle. Then, if a key fob is locatedwithin the correct regions, i.e., entry or start regions (i.e. the RSSIlevels correspond to a defined operating region) then the vehicle 105will respond to the lock/unlock and start request.

The PEPS operation of a vehicle may be triggered by way of a sensorassociated with the vehicle and may include one or more of a capacitivesensor or push button, etc.

The predetermined time period may be defined based on systemrequirements but may be for example, in the order of milliseconds.

According to a fourth aspect, the present invention provides, a systemfor detecting if a relay is present in a PEPS system for a vehicleincluding: one or more antennas associated with the vehicle fortransmitting signals from the one or more antennas to an authenticationdevice, the authentication device including a motion sensor, and one ormore controllers configured to: (a) determine whether movement of anauthentication device was detected within a predefined time period afterthe authentication device enters a PEPS entry operational region; and(b) determine if the authentication device was stationary for apredetermined time period during a PEPS entry triggering event.

According to a fifth aspect, the present invention provides, a systemfor detecting if a relay is present in a PEPS system for a vehicleincluding: one or more antennas associated with the vehicle fortransmitting signals from the one or more antennas to an authenticationdevice, the authentication device including a motion sensor, and one ormore controllers configured to: (a) determine if the authenticationdevice was stationary for a predetermined time period during a PEPSentry triggering event; and (b) upon a PEPS start sensor on the vehiclebeing triggered: (i) determine whether movement of the authenticationdevice was detected before the PEPS start sensor on the vehicle wastriggered; and (ii) determine whether the authentication device wasdetected as stationary for a predefined time period during the PEPSstart triggering event.

According to a sixth aspect, the present invention provides, a systemfor detecting if a relay is present in a PEPS system for a vehicleincluding: one or more antennas associated with the vehicle fortransmitting signals from the one or more antennas to an authenticationdevice, the authentication device including a motion sensor, and one ormore controllers configured to: (a) determine whether movement of anauthentication device was detected within a predefined time period afterthe authentication device enters a PEPS entry operational region; (b)determine if the authentication device was stationary for apredetermined time period during a PEPS entry triggering event; and (c)upon a PEPS start sensor on the vehicle being triggered: (i) determinewhether movement of the authentication device was detected before thePEPS start sensor on the vehicle was triggered; and (ii) determinewhether the authentication device was detected as stationary for apredefined time period during a PEPS start triggering event.

It will be appreciated that a controller can be located in the vehicleor the authentication device only or in both the vehicle andauthentication device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a PEPS system.

FIG. 2 is a schematic diagram illustrating a relay attack on a vehiclehaving a PEPS system.

FIG. 3 is a flow diagram illustrating the method of the presentinvention to prevent a relay attack on a vehicle having a PEPS system.

FIG. 4 is a flow diagram illustrating an embodiment of the method of thepresent invention to prevent a relay attack on the vehicle having a PEPSsystem.

DETAILED DESCRIPTION

A schematic diagram illustrating a vehicle PEPS system 100 is shown inFIG. 1 . The PEPS system 100 allows a vehicle owner (or possessor of thekey fob) to lock/unlock and start a vehicle 105 without having tointeract with the key fob 110. Typical PEPS systems define externalentry operating regions and internal start operating regions. If a keyfob 110 is located within an operating region then the vehicle 105 willrespond to lock/unlock and start requests.

The PEPS operating regions may be defined by low frequency (LF) signalmagnetic fields emitted from antennas on the vehicle. Received signalstrength indicator (RSSI) can be utilized in the key fob and the PEPSsystem may define the external operating regions and internal operatingregions using the RSSI signal levels measured from the various antennason the vehicle 105. Then, if a key fob 110 is located within the correctregions (i.e. the RSSI levels correspond to a defined operating region)then the vehicle 105 will respond to the lock/unlock and start request.

PEPS systems may be configured to have a manually triggered unlock andstart request (such as a capacitive sensor, push button and the likeprovided for example on the handle of the vehicle, or in the vehicleStart/Stop 105) to transmit the LF challenge signal 115 to the key fob110. As part of the LF challenge signal 115, signals are transmittedfrom several (or all) of the vehicles antennas. If a key fob 110 islocated within the expected operating regions (based on the RSSI valuesmeasured from the vehicle antennas), after receiving the LF challengesignal 115 it will transmit an authentication response signal on a radiofrequency (RF) 120 for the request to be processed in the vehicle. Itwill be appreciated that bi-directional RF communication may also beused.

Some PEPS systems also provide permanent periodically transmitted LFchallenge signals 115 prior to the manually triggered unlock request.For these systems, the vehicle knows when the key fob 110 is in thevicinity of the vehicle before an unlock request is made. The advantageof this is that it can improve system response times and provideadditional features such as comfort lighting as the owner approaches thevehicle 105.

As shown in the FIG. 2 , the PEPS system 200 is vulnerable to theft dueto what is known as “relay attack”. The present invention attempts toprevent a relay attack from being successful. In FIG. 2 , the relayattack involves extending the range of the LF field (shown in FIG. 1 )so that a key fob 110 which is not in proximity of the vehicle 105 willreceive the LF challenge signal. The relay attack requires two thieves,Thief A and Thief B where Thief A carries a relay receiver (Relay RX)125 and is located close to the vehicle 105 while Thief B carries arelay transmitter (Relay TX) 130 and is located close to the key fob110.

Relay RX 125 receives an LF signal from vehicle 105 and then up-convertsthe frequency to an RF frequency and transmits it via RF link to RelayTX 130. Relay TX 130 receives the RF signal and then down-converts thefrequency to LF and re-transmits the LF signal to the key fob 110. Thisscenario highlights the previously defined “analog relay”, however,other types of relays could be used. The key fob 110 automaticallytransmits an RF response upon receiving the LF challenge. The RFresponse signal will typically transmit between approximately 20-200 mback to the vehicle 105. If the vehicle 105 receives this response itwill assume that the key fob 110 is in the vicinity of the vehicle 105and so the request will be authenticated. In addition, the relay attackmethod may also be applied to extend the range of the RF response rangebeyond the transmit range of the key fob 110.

The PEPS system is also vulnerable to a “driveway attack” where it ispossible to unlock or start the vehicle 105. The “driveway attack”simply requires the thief (Thief A) to trigger the manual input unlockrequest (capacitive sensor, push button, etc. on a door handle) on thevehicle 105 and relay the LF signals using the relay receiver 125 toanother thief (Thief B) standing outside the exterior walls of thehouse. Thief B can then relay the signals into the house using the relaytransmitter 130. If the key fob 110 is situated in close proximity tothe exterior walls, for example, behind the front door of the vehicleowner's house, then the key fob 110 may receive the LF signal and sendan RF response to unlock or start the vehicle 105 upon request. Thepresent invention utilizes LF signals sent from antennas associated withvehicle 105. The first signal is a periodically transmitted signal todetermine whether the key fob 110 is moving when entering into a PEPSentry operational region and the second and third signals determineswhether the key fob 110 movement is as expected during and precedingentry and start triggering events. The present invention requires acomplicated series of movements to be satisfied in order to enter andstart the vehicle 105. For example:

-   -   1. The PEPS system uses a periodically transmitted LF challenge        signal. Movement of key fob 110 must be detected when entering        the LF field in the vicinity of a vehicle 105.    -   2. Movement of key fob 110 must be detected as “stationary” when        the entry button (or sensor) is triggered. The entry button must        be pressed before a predetermined time window has expired in        order to avoid the likelihood of a “driveway” attack.        In addition, further movements may be utilized:    -   3. Movement of the key fob 110 must be detected after the second        criteria above and before the start button (or sensor) is        triggered.    -   4. Movement of the key fob 110 must be detected “stationary”        when the start button (or sensor) is triggered.

Advantageously, the present invention allows for a vehicle 105 using aPEPS system which requires a complicated movement pattern to be detectedin order to enter and start the vehicle 105. In the present invention:

-   -   1. The key fob 110 must be moving when Thief A via relay 125,        relays the first LF signal, in order for the first stage of the        relay attack to be successful.    -   2. During the triggering of the PEPS entry sensor on the vehicle        105 the key fob 110 must be stationary, therefore the thieves        must ensure the key fob is not moving when Thief A triggers the        sensor and relays the second signal.    -   3. After the second criteria (above) has been completed the key        fob must detect movement before a start sensor on the vehicle        105 has been triggered. This represents the situation where the        owner has opened the vehicle door then moved to enter the        vehicle before triggering the vehicle start button or sensor. In        order for this stage of the relay attack to be successful the        thieves must ensure the key fob moves again after the second        criteria is completed and before Thief A triggers the start        sensor.    -   4. The key fob 110 must be detecting as stationary when the        start sensor on the vehicle 105 is triggered. This would be a        situation where the owner has sat in the driver's seat and the        key fob is “stationary” when the vehicle 105 start button or        sensor is triggered. Therefore the thieves must ensure the key        fob is not moving when Thief A triggers the start sensor and        relays the third signal.

Prior art approaches can only determine that the key fob 110 was movingat some point before the entry request, but cannot determine where thisoccurred (i.e. whether it occurred in the vicinity of the vehicle 105,or not). In addition the present invention can be implemented for motionto be detected before a start request (after detecting that the key fob110 was stationary during the entry request). This means a relay attackbecomes inherently more difficult for the thief since movement of thekey fob 110 must be in a sequence and must be initiated by two parties(Thief A, associated with relay 125, and Thief B, associated with relay130 to successfully perform a relay attack).

A flow diagram illustrating the method of the present invention is shownin FIG. 3 . In general terms the method of detecting if a relay ispresent in a PEPS system for a vehicle includes first determiningwhether any movement of an authentication device was detected within apredefined time period after the authentication device enters a PEPSentry operational region; then determining if the authentication devicewas stationary for a predetermined time period during a PEPS entrytriggering event; then upon a PEPS start sensor on the vehicle beingtriggered determining whether movement of the authentication device wasdetected before the PEPS start sensor on the vehicle was triggered andwhether the authentication device was detected as stationary for apredefined time period during the PEPS start triggering event. This maybe carried out in a number of ways including sending one or more signalsbetween the antennas associated with the vehicle and the authenticationdevice, which may take the form of a key fob or mobile communicationdevice or the like.

In the embodiment shown in FIG. 3 , the method 300 may be carried out incombination with the PEPS system associated with the vehicle 105 and anauthentication device which takes the form of a key fob 110 and acontroller (or multiple controllers). It will be appreciated that thekey fob may be an authentication device that takes the form of a mobilecommunication device or RF device or the like.

At step 305, a first signal is transmitted from one or more antennasassociated with the vehicle 305 and movement of the key fob 110 isdetected within range of the vehicle.

If the key fob 110 is moving, that indicates the owner associated withthe key fob is approaching the vehicle 105. It will be appreciated thatthe first signal may be repeatedly sent, i.e. in a polling arrangementto detect movement of the key fob 110.

Control then moves to step 310 where a second signal is transmitted fromthe one or more antennas associated with the vehicle 105 and, at thetime an entry sensor on the vehicle 105 being triggered, determineswhether or not the key fob 110 is stationary before a predetermined timeperiod has elapsed.

Control then moves to step 315 where a third signal is transmitted fromthe one or more antennas associated with the vehicle 105 and, at thetime of a start sensor on the vehicle 105 being triggered, determineswhether or not the key fob 110 was in motion (after the precedingstationary period during entry) and is stationary during the starttriggering event before a predetermined time period has elapsed. Thefirst signal, second signal and third signal may be an LF signal or RFsignal depending on the authentication device (i.e. key fob or mobilecommunication device).

While the present invention may simply provide steps 305, 310 and 315 tocontrol access and avoid a relay attack, however, it is possible forsystems to use only steps 305 and 310 or only steps 310 and 315 withreduced effectiveness of the relay attack countermeasure.

FIG. 4 is a flow diagram illustrating an exemplary embodiment of theinvention in operation. The method 400 may be carried out on the vehicle105 having a PEPS system together with the key fob 110 and a controller(or multiple controllers) associated with the PEPS system 100.

At step 405, the vehicle 105 periodically transmits an LF challengesignal (i.e., a polled signal). Control then moves to step 410 where itis determined whether or not the periodically transmitted LF message hasbeen detected by the key fob 110. If it has not been detected controlreturns to step 405 where the LF message is sent again until such timeas the LF message is detected by the key fob 110 at which time controlmoves to step 415. At step 415 it is determined whether or not motion isdetected in the key fob 110 during receipt of the LF message. It will beappreciated that the key fob 110 includes a motion sensor or the like,such as an accelerometer. Movement of the key fob 110 must be detectedwhen entering the LF field within a particular time period in thevicinity of the vehicle.

It will be appreciated that the time gap between the periodicallytransmitted LF messages must be considered as a system error and if thekey fob 110 is stationary when receiving the first LF message the motionduring the gap time period must also be considered. For example, if thetime between the periodically transmitted LF signal is 300 ms, it ispossible that the key fob 110 enters the LF field region during this 300ms. It is also possible for example that the key fob 110 is in a bagassociated with the owner and might be placed stationary on the groundwithin this 300 ms timeframe and as will be appreciated, the key fob 110will then be stationary when it receives the first LF message.Therefore, the key fob 110 must determine whether it was in motionwithin a predetermined time period (i.e. 300 ms) before receiving the LFmessage.

As noted above, at step 415 it is determined whether or not there ismotion of the key fob 110 during reception of the LF message, if thereis not, then control moves to step 420 where the key fob 110 may bedisabled since it is possible that there is a relay attack occurring.Otherwise, control moves to step 425 where the key fob 110 transmits aresponse to the vehicle 105. The response may be a UHF response and itmay occur within a predetermined time period.

After entering the LF field, the vehicle 105 continues to send periodicLF messages. If the key fob 110 was detected to be stationary after apredetermined time, the key fob will not send a response at step 430(this feature is used to prevent a possible “driveway” attack). Thevehicle 105 may provide an indication to the vehicle owner that the timewindow has expired by, for example, flashing the lights, sounding thehorn or some other method in order to tell the vehicle owner toreactivate the key fob 110 by moving it. If at step 430, the PEPS entrybutton is not triggered before the predetermined time window hasexpired, control moves to step 431 where the vehicle continues to pollperiodically and determine whether the key fob is still within the PEPSentry region. If at step 432, it is no longer detected in the regioncontrol returns to step 405. However, if the key fob is detected withinthe PEPS entry region at step 432, then control moves to step 433 whereif the key fob 110 detects motion again, control returns to step 430.

When the PEPS entry button is triggered before the predetermined timewindow has expired, control moves to step 435 where the vehicletransmits another LF challenge signal. Control then moves to step 440where it is determined whether or not the key fob 110 has beenstationary during the triggering event for a predetermined time periodbefore the key fob 110 transmits a UHF response at step 445. If the keyfob 110 was not stationary for a predetermined time period at step 440control returns to step 430. Otherwise, control moves to step 445 whenthe key fob 110 transmits the UHF response.

Control then moves to step 450 where it is detected that entry and(unlocking step 455) has been permitted. At step 460 it is determinedwhether or not there is a movement in the key fob 110 at this point.Movement of the key fob 110 must be detected after entry has beenpermitted at step 450 and 455 and before the start button is triggeredat step 465. At step 465, when the start button is triggered, another LFchallenge signal is transmitted by the vehicle at step 470.

Control then moves to step 475 where the key fob 110 must be determinedas being stationary for a predetermined time period before control movesto step 480, otherwise control returns to step 465.

At step 480 the key fob 110 transmits a UHF response and the vehiclestart process may be performed at step 485 and 490.

It will be appreciated that the key fob 110 does not necessarily need tosend a response to the vehicle after receiving the LF challenge signal,that is, the key fob 110 may simply record that it was in motion whenentering the LF field. When the entry LF challenge is received by thekey fob 110 it will only respond (with a positive response) if at theinitial periodically transmitted LF message motion was recorded.

It will also be appreciated that other polling regions may be added. Forexample, when the key fob 110 is detected moving in, for example anouter LF field region, the LF transmit power of the vehicle antennas canbe reduced (or the accepted RSSI's for the region can be increased) tomake a smaller LF operating region within the outer region. The key fob110 must be found to be moving when entering into this smaller regionfor example. If additional polling regions are used, the decision onwhether the key fob 110 is ‘stationary’ or ‘moving’ upon entering themultiple polling regions must be performed multiple times therebyfurther complicating the movement pattern thieves must replicate toperform a successful relay attack.

It will also be appreciated that a restriction on the number of times akey fob 110 may enter or exit the LF field region may be implemented inorder to restrict the number of times a user (or thief) can attempt toenter the vehicle 105.

While the present invention has been described with regard to a key fob110 and LF signals, the method could equally apply to a RF system wherea mobile phone (or other RF device) with a motion sensor is used inplace of a key fob 110. In this case, the first signal may betransmitted from the authentication device or the vehicle. The secondand third signals should be transmitted from the vehicle during PEPStriggering events.

The claims defining the invention are as follows:
 1. A method ofdetecting if a relay is present in a PEPS system for a vehicle, themethod comprising: (a) determining via a periodically transmitted LF orRF challenge signal whether movement of an authentication device wasdetected within a predefined time period after the authentication deviceenters at least one of a PEPS entry operational region or sub-region,the sub-region being a smaller LF operating region within the PEPS entryoperational region, wherein at least the PEPS entry operational regionis defined by: LF or RF or magnetic fields emitted from antennasassociated with the vehicle, and RSSI signal levels measured from theantennas associated with the vehicle; and (b) determining via aperiodically transmitted LF or RF challenge signal if the authenticationdevice was stationary in at least one of the PEPS entry operationalregion or sub-region for a predetermined time period during a PEPS entrytriggering event.
 2. A method of detecting if a relay is present in aPEPS system for a vehicle, the method comprising: (a) determining via aperiodically transmitted LF or RF challenge signal if an authenticationdevice was within at least one of a PEPS entry operational region orsub-region, the sub-region being a smaller LF operating region withinthe PEPS entry operational region, and stationary for a predeterminedtime period during a PEPS entry triggering event; and (b) upon a PEPSstart sensor on the vehicle being triggered, performing the following:i. determining via a periodically transmitted LF or RF challenge signalwhether movement of the authentication device was detected within thePEPS entry operational region before the PEPS start sensor on thevehicle was triggered; and ii. determining via a periodicallytransmitted LF or RF challenge signal whether the authentication devicewas detected within the sub-region as stationary for a predefined timeperiod during the PEPS start triggering event.
 3. A method of detectingif a relay is present in a PEPS system for a vehicle, the methodcomprising: (a) determining via a periodically transmitted LF or RFchallenge signal whether movement of an authentication device wasdetected within a predefined time period after the authentication deviceentered at least one of aPEPS entry operational region or sub-region,the sub-region being a smaller LF operating region within the PEPS entryoperational region, wherein the PEPS entry operational region is definedby: LF or RF magnetic fields emitted from antennas associated with thevehicle, and RSSI signal levels measured from the antennas associatedwith the vehicle; and (b) determining via a periodically transmitted LFor RF challenge signal if the authentication device was within at leastone of a PEPS entry operational region or sub-region, the sub-regionbeing a smaller LF operating region within the PEPS entry operationalregion, and stationary for a predetermined time period during a PEPSentry triggering event; and (c) upon a PEPS start sensor on the vehiclebeing triggered, performing the following: i. determining via aperiodically transmitted LF or RF challenge signal whether movement ofan authentication device was detected within the PEPS entry operationalregion before the PEPS start sensor on the vehicle was triggered; andii. determining via a periodically transmitted LF or RF challenge signalwhether the authentication device was detected within the sub-region asstationary for a predefined time period during the PEPS start triggeringevent.
 4. The method of claim 2, wherein the predetermined time periodis defined based on system requirements.
 5. A system for detecting if arelay is present in a PEPS system for a vehicle, comprising: one or moreantennas associated with the vehicle for transmitting signals from theone or more antennas to an authentication device, wherein theauthentication device includes a motion sensor; and one or morecontrollers, each of which is configured to perform the following: (a)determining via a periodically transmitted LF or RF challenge signalwhether movement of an authentication device was detected within apredefined time period after the authentication device enters at leastone of a PEPS entry operational region or sub-region, the sub-regionbeing a smaller LF operating region within the PEPS entry operationalregion, wherein the PEPS entry operational region is defined by: LF orRF or magnetic fields emitted from antennas associated with the vehicle,and RSSI signal levels measured from the antennas associated with thevehicle; and (b) determining via a periodically transmitted LF or RFchallenge signal if the authentication device was stationary in at leastone of the PEPS entry operational region or sub-region for apredetermined time period during a PEPS entry triggering event.
 6. Asystem for detecting if a relay is present in a PEPS system for avehicle, comprising: one or more antennas associated with the vehiclefor transmitting signals from the one or more antennas to anauthentication device, wherein the authentication device includes amotion sensor; and one or more controllers, each of which is configuredto perform the following: (a) determine via a periodically transmittedLF or RF challenge signal if the authentication device was within atleast one of a PEPS entry operational region or sub-region, thesub-region being a smaller LF operating region within the PEPS entryoperational region, and stationary for a predetermined time periodduring a PEPS entry triggering event; and (b) upon a PEPS start sensoron the vehicle being triggered, performing the following: i. determiningvia a periodically transmitted LF or RF challenge signal whethermovement of an authentication device was detected within the PEPS entryoperational region before the PEPS start sensor on the vehicle wastriggered; and ii. determining via a periodically transmitted LF or RFchallenge signal whether the authentication device was detected withinthe sub-region as stationary for a predefined time period during thePEPS start triggering event.
 7. A system for detecting if a relay ispresent in a PEPS system for a vehicle, comprising: one or more antennasassociated with the vehicle for transmitting signals from the one ormore antennas to an authentication device, wherein the authenticationdevice includes a motion sensor; and one or more controllers, each ofwhich is configured to perform the following: (a) determining via aperiodically transmitted LF or RF challenge signal whether movement ofan authentication device was detected within a predefined time periodafter the authentication device enters at least one of a PEPS entryoperational region or sub-region, the sub region being a smaller LFoperating region within the PEPS entry operational region, wherein thePEPS entry operational region is defined by: LF or RF magnetic fieldsemitted from antennas associated with the vehicle, and RSSI signallevels measured from the antennas associated with the vehicle; (b)determining via a periodically transmitted LF or RF challenge signal ifthe authentication device was within at least one of a PEPS entryoperational region or sub-region, the sub-region being a smaller LFoperating region within the PEPS entry operational region, andstationary for a predetermined time period during a PEPS entrytriggering event; and (c) upon a PEPS start sensor on the vehicle beingtriggered, performing the following: i. determining via a periodicallytransmitted LF or RF challenge signal whether movement of theauthentication device was detected within the PEPS entry operationalregion before the PEPS start sensor on the vehicle was triggered; andii. determining via a periodically transmitted LF or RF challenge signalwhether the authentication device was detected within the sub-region asstationary for a predefined time period during a PEPS start triggeringevent.
 8. The system of claim 5, wherein the controller is only locatedin the vehicle or the authentication device.
 9. The system of claim 5,wherein a controller is located in both the vehicle and theauthentication device.